Since titanium alloy is light-weight and exhibits a high strength (since it exhibits a large specific strength), it has been used in the fields of aviation, military, ocean, space, and the like. However, since titanium alloy is usually poor in terms of the working property and forming property, the material yield has been poor and accordingly titanium products has been expensive in general. Therefore, its usage range has been limited.
Recently, a titanium alloy (for example, Ti-22V-4Al: a trade name “DAT51,” etc.), which is relatively good in terms of the working property, titanium products have been increasing around us. However, it has not been possible yet to say that the working property is sufficient, and, when a working ratio enlarges, there often arises a case where the ductility lowers sharply. Therefore, when a titanium alloy, which is good in terms of the working property, is available, the material yield of titanium products is improved, and accordingly it is possible to intend the increment of production volume, the further expansion of usage, and the like.
Moreover, in order to intend the usage expansion of titanium products, in addition to such a working property, a titanium alloy, which exhibits a low Young's modulus and a high strength, has been required. When such a titanium alloy is available, the degree of designing freedom of a variety of products is sharply upgraded to such an extent that cannot be achieved by conventional materials. For instance, when a titanium alloy, which exhibits a low Young's modulus and a high strength, is used in the heads of golf clubs, it is possible to reduce the natural frequencies at the face portions, and accordingly it is possible to synchronize the natural frequencies at the face portions with the natural frequencies of golf balls. Thus, it is said that it is possible to obtain golf clubs, which can remarkably extend the driving distance of golf balls. In addition, for example, when a titanium alloy, which exhibits a low Young's modulus and a high strength, is used in the frames (especially the temple portions) of eyeglasses, a superb fitting feeling is available, and, together with the light-weightness, allergic resistance, and so on, it is said that the functional properties are greatly enhanced.
Thus, when a titanium alloy, which is provided with not only a superb working property but also a low Young's modulus as well as a high strength, is developed, it is believed that the demand of titanium alloy members (titanium products), which use it, expands more and more.